A METHOD OF PREPARING SPHERICAL NANO-CRYSTAL CELLULOSE WITH MIXED CRYSTALLINE FORMS OF CELLULOSE Ⅰ AND Ⅱ

A new kind of nano-crysta cellulose (NCC) prepared from natural cotton fiber has been obtained by the method ofacid hydrolysis. Compared to most other nanophase materials that derive from inorganic materials, our products are preparedfrom natural cotton fibers. The products are of spherical shape with mixed crystal forms of cellulose I and II. The preparationconditions determine the properties of the products. Prior treatment is a critical procedure. The properties of the products arealso strongly affected by such conditions as the kinds of acids used, the ratio of the acid mixture, the acid concentration, theultrasonic agitation time and hydrolysis temperature. The number average molecular weight of NCC is determined by gelpermeation chromatography (GPC). The particle size and shape were determined by transmission electron microscopy(TEM). X-ray diffraction was used to detect the crystallinity and average crystallite size of the panicle.

克拉霉素的晶型及其转换

克拉霉素与柠檬酸成盐,在乙醇-水、丙酮-水、异丙醇-水(1∶1)中调碱,或与酒石酸成盐,在乙醇-水、丙酮-水(1∶1)中调碱,在常压60℃下干燥,DSC分析证明该晶型为FormⅡ.该工艺避免了真空高温干燥的转晶条件,易于工业化生成.同时得到了克拉霉素的乙腈加成物单晶:P21晶型,a=1.064 4(2)nm,b=1.809 9(4)nm,c=1.162 8(2)nm,α=γ=90°,β=95.38(3)°,V=2.230 1(8)nm3,Z=2,Dc=1.175 g.cm-3,μ=0.087 mm-1,F(000)=860,R1=0.034,wR2=0.062.

pH值对啶酰菌胺晶型的影响

采用不同有机碱用量的实验条件获得了不同晶型的啶酰菌胺,利用DSC、XRD等分析手段,对啶酰菌胺晶体进行了表征。研究了结晶时p H值对啶酰菌胺析出晶型的影响,讨论了获得啶酰菌胺的单一晶型所需的p H条件,获得了制备啶酰菌胺单一晶型的方法。